Installing a roof window

Which roof window to choose?

To choose the right window frame, you will first need to take a few measurements. Check the following:

• The roof pitch (X)
• The window height (Y)
• The distance between the top of the frame and the room floor (H)
• The distance between the bottom of the frame and the room floor (A)
• Choose between the opening systems: top-hung or centre-pivot

The windows are supplied in ready-to-install kits. They may include accessories such as blinds (roller, pleated, venetian, blackout) or mosquito nets or shutters.

Preparing the roof

To create the opening in which to insert the window, remove the roof tiles from the covering.

Mark the joists to be cut, considering the thickness of the beams you will install plus a 5cm tolerance.

At this point, cut the trusses after having propped up the beams beforehand.

Install the new joists by screwing them at the ends with roof screws.

Secure the trusses to the new joists using the brackets.

If necessary, adjust the trusses to match the width of the window.

Installing the roof window

To make the installation easier, remove the first row of tiles near the opening. Now remove the sash from the frame and install the frame.

Secure the frame with brackets to the battens, making sure it is square. To do this, measure the diagonals of the sub-frame, which should be identical.

Follow the tolerances specified by the window manufacturer for the final waterproof cladding.

Window flashing

In the final phase, we will install the waterproofing kit supplied with the window. Position the lower lead apron (c) and secure it with the metal strip that covers it.

Press the lead onto the roofing material using a wooden mallet. Now place the side flashing pieces (e).

Insert the top cap (f) over the side flashing pieces and secure it with screws. Remember to reposition the tiles around the frame, leaving enough space uncovered for water and snow drainage. If you need to cut tiles, you can use an angle grinder with an appropriate masonry disc.

Replace the sash on the frame. The installation principle is similar for every model and manufacturer, but I recommend checking the instructions provided by the manufacturer.